Keeping Secrets

Cryptography, from the Greek word for “secret writing,” is the science of communication over untrusted communications channels. Historically, cryptography has been associated with spies, governments, and the military. It has been used in warfare for thousands of years, with some of the most famous cases, including the German Enigma machine, coming from World War II. Over the last 50 years, however, cryptography has acquired a sound mathematical and practical foundation and has moved from being a tool of military and diplomatic application to one that embraces commercial applications as well.

When used properly, cryptography can keep a message secret, positively identify its sender, and assure the recipient that it was not modified in transit. In some cases, cryptographic techniques can help prove that a message was sent in the first place, and by whom.